In the course of the electrification of the drive trains in the automobile industry (completely electronically driven vehicles or hybrid vehicles), more and more so-called onboard chargers (OBC), or chargers which are integrated in the vehicle for the vehicle batteries are being used to charge the accumulator of the vehicle. In these chargers, EMC (electromagnetic compatibility) filters are used to comply with EMC requirements. For this, a customary interference-suppression measure is to use radio-interference-suppression capacitors of the classes x and y (referred to below as x capacitors and y capacitors).
This is illustrated figuratively in FIG. 1. A vehicle F having an electric motor or hybrid drive system is provided with a charger OBC for the vehicle batteries. For supplying energy via a charging cable, a charging pillar or a wallbox, terminals are provided for an outer conductor L, a neutral conductor N and a protective conductor PE. In order to suppress interference, x capacitors (Cx in FIG. 1) and y capacitors (Cy1 and Cy2 in FIG. 1) are arranged in the vehicle F. If the supply voltage of the vehicle is disconnected, energy is still stored in these capacitors. Therefore, there is still a residual voltage at the capacitors and therefore at the charging socket of the vehicle. The capacitors must firstly discharge via correspondingly provided resistors (Rx, Ry1, Ry2 in FIG. 1) before there is no longer any voltage at the charging interface of the vehicle F. In order to ensure the protection of the user, the requirement with respect to the rate of decrease in this residual voltage is specified in corresponding product standards (e.g. in the standard DIN EN 61851-1).
Since the discharging resistor Rx is also connected to the supply voltage during normal operation, the discharge resistor Rx also generates a power loss during normal operation, i.e. during the charging process, which power loss reduces the efficiency of the charger OBC. In order to limit these losses to a minimum, attempts are made to select the resistor Rx to be as large as possible. However, this dimensioning is subject to limits owing to the standard requirements with respect to a rapid voltage drop of the residual voltage which is stored in the capacitors. This is because the voltage drop of the voltage which is present at the capacitor Cx approximately obeys an exponential function with the product Rx*Cx as a time constant, i.e.U(t)=Uo*exp(−t/T), where T=Rx*Cx. 
In order to bring about the voltage drop within the limits specified by the standards, T must not be selected to be too large. In addition to aiming for the largest possible value for the resistor Rx, efforts are frequently made also to select the value for the capacitor Cx to be as large as possible in order to permit a good EMC behavior. The definition of the values for Rx and Cx therefore always constitutes a compromise between the EMC behavior and the power loss or efficiency during normal operation. This compromise usually leads to a situation in which the standard is interpreted as widely as possible or its possibilities utilized as far as possible.